seems like a bit of a stretch but it may be true

Instagram and Facebook use similar algorithms to suggest friends and accounts to users. The algorithm takes into account various factors such as location, mutual friends, interests, and activity.

It's likely that the algorithm suggested your former football teammate to you on Instagram because it detected that you two were in close proximity to each other at the same time, likely in the supermarket. It's also possible that the algorithm took into account the fact that you exchanged numbers, as this could indicate a potential connection.

It's also possible that the algorithm took into account your search on Facebook, as searching for someone's name on the platform could indicate an interest in connecting with that person. However, it's important to note that Instagram and Facebook are separate platforms, so they do not share data directly.

It's also possible that you might have been looking for something similar on Instagram or Facebook, and that's how the algorithm suggested him, or that the algorithm noticed that he was searching for you too.

It's also possible that you have some common friends on Instagram which the algorithm took into account.

It's difficult to say for certain how the algorithm worked in this specific situation without access to your personal data and without more information about your activity on both platforms. But generally, these are the factors that algorithms take into account to suggest users and accounts.

Verry good idea

É porque o Facebook e o Instagram estão conectados ao seu telefone e quando você pesquisa em um local da Internet, ambos os aps veem sua atividade e a usam. É por isso que você tem uma sugestão sobre um enquanto apenas pesquisou sobre o outro

You gave him your number and he finally added you to his contacts after three days and that’s when instagram recommended him because he had your number in his contacts synced to his instagram

I have two possible answers
1.both instagram and facebook are owned by meta
2.instagram syncs with your contact and suggests the people on that particular contactbook

Si es verdad, deberían cancelarlos todos, antes estaba mejor,

Sugestões no Instagram são pessoas que visitaram seu perfil, mas também pode ser a sua atividade na tua conta Google, com base em contatos, interesses, etc.